The merits of zinc and aluminium have been debated since their introduction to lithography. Each metal has had strong advocates, and excellent work has been produced over the years using both materials. From the practical viewpoint, there is little difference between the two metals in cost, outlay of processing materials, and easy of printing. It is safe to say that each type of plate, when handled knowledgeably will perform equally well. The choice of wether to stock one or both types of plates and suitable processing materials for each is largely dependant on the subjectives of the lithography shop. It might be advisable for school shops to stock only one metal in order to minimize cost and to avoid confusion and contamination of the processing materials necessary for both types of plates. The following chart comparing the merits of the two metals will serve as a basic guide:

Zinc

Aluminium

Darker surface colour, somewhat detrimental for close-valued tonal drawing. Crayon and wash drawings appear markedly different from those on stone

Lighter surface colour, easier to see the drawing of close tonal work. Crayon and wash drawing appear more nearly like those on stone.